transmission electrical issues

[bikeguy]

I can be driving fine then all of a sudden speedometer goes nuts bouncing from 50 to 100 and back then it drops out of gear and wont shift out of second gear any ideas are worth a try it has got me puzzled

[HenryJ]

Doesn't sound good. Does it continue or reset on restart? Second gear is limp mode.

I have heard of sun shell issues. I have seen the planetary fail. Trans did not last long on that one. Limped in second gear. No reverse. Rebuild was the only answer.

[bikeguy]

does not reset but I still have reverse I love my 02 sr5 and I am ready to be back in it

[Built2Bend]

I'm just throwing this out there. But isent the speedo on are trannys I know the 700r4 is but they may have changed it for the 4l60e. My question is could the speedo be reading wrong. And jumping every where and after the PCM sees the speedo freaking out goes into limp mode becoulse it thinks some thing major is wrong. I'm not very we'll versed in trans yet so don't trust my words to the letter. But if what I sed above would check out. It posible just a speedo cable or something similar. If what I sed isent possible. Or I corect please delete this post I don't want to clog up a thread with false information.

[HenryJ]

Have you tried removing the battery cables to reset the control modules? Take loose both cables, clean them and wait three minutes before reattaching. This is time for capacitors in the system to discharge.
Make sure when you reattach them that they are indeed tight. The bolt can bottom out in the hole and leave the cable still loose. A loose battery cable connection could be the problem?

[bikeguy]

new batt and cables installed after first episode also changed trans filter and fluid the fluid was not burnt at all I was told it could be speed sensor or insterment cluster does this sound possible

[HenryJ]

The trans going into limp mode has me still searching. The bouncing speedometer is just a bad stepper motor in the instrument cluster. Those are pretty common. I have had to replace several of those on fullsize trucks. They don't put the tranny in limp mode though. I have seen the engine go into limp mode due to the brittle wiring near the throttle body on drive by wire trucks. You don't have that problem. VSS maybe? I am still skeptical though. A VSS is a pretty simple sensor. It is just a pick up for a pulse. Don't get me wrong, I have had them fail. I have not had issues like you describe from the failures that I have seen.
Do you have any aftermarket electronics?
The Autogauge meter that installs into the diagnostic port caused problems that are similar in my wife's car. It was somehow corrupting the serial data.

Have you done a body lift? Hobie stressed the wires to his PCM and had transmission problems afterwards.

OK, back to your filter replacement. The pan can be difficult to install if you don't use some finesse. More than one has forced it and broken a solenoid , or cracked a connector. I hate to say pull the pan again, but that might have to happen?

[bikeguy]

the truck is stock all the way only thing not original is replaced radiator it was doing this before filter change

[HenryJ]

Did this all start after the filter change? Did it start after the cables and battery change? How many miles on the truck? Reading your post above you did not start working on it until after the first "episode".
If that is true and you don't have any further suspect , clues , or leads at this point, I am afraid you are going to have to seek assistance in getting more clues. I may be possible that there are transmission codes stored. That will likely need the assistance of a GM technician and his TechII.
If you think repairing the instrument cluster might help, you could proceed that direction. I still have my old BCM on the shelf if you need one. Speedometer information is stored there. It would not be a VIN match and again you would need to seek the assistance of the GM Tech.
I am leaning toward the transmission being the problem. The whole kicking into neutral thing being my biggest push that direction. It may be just a solenoid of connection in there. I am no transmission guru. I would have to take it somewhere for help. Plan on a rebuild being around $1500

[bikeguy]

only work prior to episode #1 was radiator replace mileage is 101462

[ApproachMedium]

Have the codes read. My truck behaved the same way when my speed sensor went. I had erratic speedo either was not picking up right speed or jumping around. Trans would not shift right. Changed sensor everything was right with the world.

Whats funny, is this exact same thing happens with the locomotives at work with the electric traction motors. With a locomotive though it just disables the motor with the failing speed sensor, but for each motor you loose you loose that much more power to pull the train.

[HenryJ]

Have the codes read. My truck behaved the same way when my speed sensor went...

sounds like best advice yet

[bikeguy]

thanks fella's I am having it looked at next week

[ApproachMedium]

Great. Good luck! Hopefully its just something stupid.

[Hartleybl]

I second the speed sensor on the tcase mine did that drove 40 miles to the nearest parts store down the interstate in 2nd... Had 33's and 3.42s so it wasn't to bad but still... Vss was it

[bikeguy]

well come to find out all it was is a short in the 2-3 shift solenoid $27 and new filter and fluid total $92 and we should be rollin in the dirt tomarrow thanks for all the input and support fellas I was ready to drive the bad four letter f word but I like it sittin in the yard cant wait for sunrise tommarrow heck yeah rollin again